linux-kernel - Re: [RFC][PATCH 4/5] memory_pressure

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Message-ID: <cfd9edbf0801180224r3ddf1940h4245e2feff488486@mail.gmail.com>
Date:	Fri, 18 Jan 2008 11:24:27 +0100
From:	"Daniel Spång" <daniel.spang@...il.com>
To:	"KOSAKI Motohiro" <kosaki.motohiro@...fujitsu.com>
Cc:	"Rik van Riel" <riel@...hat.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	"Marcelo Tosatti" <marcelo@...ck.org>,
	"Andrew Morton" <akpm@...ux-foundation.org>
Subject: Re: [RFC][PATCH 4/5] memory_pressure_notify() caller

On 1/17/08, KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> wrote:
> Hi Daniel
>
> > > Thank you for good point out!
> > > Could you please post your test program and reproduced method?
> >
> > Sure:
> >
> > 1. Fill almost all available memory with page cache in a system without swap.
> > 2. Run attached alloc-test program.
> > 3. Notification fires when page cache is reclaimed.
>
> Unfortunately, I can't reproduce it.
>
> my machine
>         CPU:    Pentium4 2.8GHz with HT
>         memory: 512M
>
>
> 1. I doubt ZONE_DMA, please shipment ignore zone_dma patch(below).
> 2. Could you please send your .config and /etc/sysctl.conf?
>    I hope more reproduce challenge.
>
> thanks.
>
> - kosaki
>
>
>
>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
>
> ---
>  include/linux/mem_notify.h |    3 +++
>  mm/page_alloc.c            |    6 +++++-
>  2 files changed, 8 insertions(+), 1 deletion(-)
>
> Index: linux-2.6.24-rc6-mm1-memnotify/include/linux/mem_notify.h
> ===================================================================
> --- linux-2.6.24-rc6-mm1-memnotify.orig/include/linux/mem_notify.h
>  2008-01-16 21:31:09.000000000 +0900
> +++ linux-2.6.24-rc6-mm1-memnotify/include/linux/mem_notify.h
> 2008-01-16 21:34:24.000000000 +0900
> @@ -22,6 +22,9 @@ static inline void memory_pressure_notif
>         unsigned long target;
>         unsigned long pages_high, pages_free, pages_reserve;
>
> +       if (unlikely(zone->mem_notify_status == -1))
> +               return;
> +
>         if (pressure) {
>                 target = atomic_long_read(&last_mem_notify) + MEM_NOTIFY_FREQ;
>                 if (likely(time_before(jiffies, target)))
> Index: linux-2.6.24-rc6-mm1-memnotify/mm/page_alloc.c
> ===================================================================
> --- linux-2.6.24-rc6-mm1-memnotify.orig/mm/page_alloc.c 2008-01-13
> 19:50:27.000000000 +0900
> +++ linux-2.6.24-rc6-mm1-memnotify/mm/page_alloc.c      2008-01-16
> 21:41:58.000000000 +0900
> @@ -3467,7 +3467,11 @@ static void __meminit free_area_init_cor
>                 zone->zone_pgdat = pgdat;
>
>                 zone->prev_priority = DEF_PRIORITY;
> -               zone->mem_notify_status = 0;
> +
> +               if (zone->present_pages < (pgdat->node_present_pages / 10))
> +                       zone->mem_notify_status = -1;
> +               else
> +                       zone->mem_notify_status = 0;
>
>                 zone_pcp_init(zone);
>                 INIT_LIST_HEAD(&zone->active_list);

Your patch above solves the problem I had with early notification.

Cheers,
Daniel
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